Abstract
Influence of accumulative passing tonnage on fatigue crack growth in rail steels was investigated. The fatigue crack growth was measured using compact tension specimens cut from three kinds of rails with accumulative passing tonnage of 100MGT, 200MGT, 600MGT respectively. The fatigue crack growth rate was estimated by the effective stress intensity range ΔKeff obtained by an unloading elastic compliance method. In addition, the measurements of crack opening displacement and the analysis of fatigue fracture surfaces were carried out to clarify the mechanism of crack closure behavior by a scanning electron microscope. It was concluded that the roughness of fatigue crack surface dependent on the grain size of each rail steel influences the crack growth behavior, and that the influence of accumulative passing tonnage on fatigue crack growth behavior can be estimated by the threshold effective stress intensity range ΔKeff, th.
